1. Field of the Invention
The present invention relates to a solid-state image sensor, and more particularly, to a solid-state image sensor used in a digital camera or video camera.
2. Description of the Related Art
In recent years, from the viewpoint of making digital cameras more compact in size, a solid-state image sensor which corresponds to a camera lens having a short back focus has been demanded. Furthermore, from the viewpoint of expanding the dynamic range of a digital camera, there have been demands to use a solid-state image sensor having a large size in compact digital cameras. In a digital camera which is subject to requirements of this kind, since the light beam is input at a widely inclined angle to the pixels in the peripheral region of the solid-state image sensor, the sensitivity of the pixels in the peripheral region is reduced.
In view of this problem, Japanese Patent Application Publication No. 2010-182765 discloses a solid-state image sensor in which microlenses provided on pixel surfaces are situated eccentrically with respect to the central direction of the solid-state image sensor, whereby it is possible to detect, with good accuracy, a light beam input at an inclined angle with respect to the pixels.
On the other hand, focal point detection technology is also available in digital cameras. Japanese Patent No. 04835136 discloses, in respect to this technology, a solid-state image sensor which has a composition for focal point detection by a phase differential method in a portion of the pixels of a solid-state image sensor. A phase differential method is a method which compares the images of light passing through different regions of the pupil of an imaging optical system, and detects a depth by triangulation based on the stereo images.